This invention relates generally to automatic swimming pool cleaners of the type which use a cleaner body for movement through a water pool to remove dirt from the water and/or containment wall surfaces. Various pool cleaner configurations are shown in the prior art including cleaners that are powered by positive pressure water flow, negative pressure (i.e., suction) water flow, and electricity to propel a cleaner body forwardly through a water pool. Further, many such pool cleaners include timer mechanisms which periodically initiate a xe2x80x9cbackupxe2x80x9d state to propel the body in a reverse direction. The inclusion of a backup state reduces the likelihood of the body getting trapped behind an obstruction for an extended period.
At least one prior patent, i.e., U.S. Pat. No. 4,100,641 issued to Pansini, describes a cleaner which is propelled in either first or second opposite directions and which responds to the cleaner slowing down or stopping, to switch directions.
The aforementioned International Applications PCT/US98/27623 and PCT/US98/27622 disclose automatic swimming pool cleaning systems respectively powered by positive pressure and negative pressure sources. Both applications disclose multiple embodiments which include a cleaner body carrying a propulsion subsystem for producing a force to propel the body in a forward direction. The actual motion and orientation of the body at any instant in time is determined by the net effect of several forces variably acting on the body, e.g., the propulsion force, drag forces attributable to the power source hose, contact forces exerted by the wall surfaces and obstruction surfaces (e.g., ladder, steps, etc.), etc. As a consequence, the cleaner body typically traverses an essentially random path through the pool as it is propelled in a forward direction by the propulsion force. Although the body is preferably configured so that the propulsion force causes the body to generally glance off or work its way around most obstructions, situations can occur when an obstruction, acting in conjunction with the propulsion force, traps the body in a particular location. In order to avoid such trapping, the aforementioned applications disclose embodiments (e.g., FIGS. 13, 23 in PCT/US98/27623 and FIGS. 22, 26 in PCT/US98/27622) which include a motion sensor which functions to indicate when the body""s forward motion diminishes below a certain threshold rate. The motion sensor indication is then used to exert an additional force on the body for a limited duration to change (e.g., rotate and/or translate) the body""s position. Thereafter, the propulsion force propels the body forwardly enabling the body to avoid the obstruction and randomly traverse the pool.
Although the embodiments specifically described in the aforecited international applications relate primarily to cleaner bodies capable of selectively operating proximate to both the water surface and wall surface, the concept of sensing cleaner body motion to initiate a limited duration repositioning force is applicable to a wide variety of automatic swimming pool cleaners including cleaners intended to operate (1) solely near the wall surface and (2) solely near the water surface. Such cleaners can be powered by a variety of sources including positive pressure and/or negative pressure hydraulic and pneumatic sources as well as electric power sources. The specific preferred embodiments described herein are primarily intended for use with wall surface cleaner bodies driven by positive water pressure sources.
The present invention relates to automatic swimming pool cleaning systems including a cleaner body intended to travel in a forward direction to substantially randomly traverse a swimming pool. Systems in accordance with the invention include a propulsion subsystem for producing a force to propel the body in a forward direction, a motion sensor for indicating when the velocity of the body, diminishes below a certain threshold rate, and a repositioning subsystem responsive to said motion sensor indication for producing a limited duration force to change the position of the body.
More particularly, systems in accordance with the invention contemplate that the body travel in a forward direction for extended periods of time. In the event, the motion sensor recognizes that the body""s velocity has diminished below a certain threshold, then the repositioning subsystem is activated to apply a repositioning force for a limited duration, e.g., from 1 to 60 seconds, to reposition the body. The repositioning force in accordance with the invention can be produced in various ways; e.g., (1) by discharging a water flow to develop a reactive force or (2) by activating a mechanism to mechanically develop a rotation and/or translation force. The propulsion subsystem can continue to produce the propulsion force during the limited duration repositioning or, alternatively, it can be interrupted.
A repositioning subsystem in accordance with the invention can be implemented in various manners. For example, it can be configured to be housed in the cleaner body or in a housing carried by a conduit supplying power to drive the cleaner body. The conduit, can for example, comprise a hose for carrying water to or from an externally mounted pump. Alternatively, the conduit can contain electric wires for powering a mechanism on board the cleaner body.
A conduit in a typical swimming pool situation is about 20-45 feet in length and can be comprised of multiple elongate sections coupled together. The conduit should be flexible over its length to allow the cleaner body to randomly traverse the pool without excessive restraint being imposed by the conduit. In accordance with preferred embodiments of the present invention, the portion of the conduit connected to the cleaner body, i.e., the distal conduit section, should exhibit sufficient torsional stiffness to enable the cleaner body to reposition (1) by rotating the body relative to the conduit axis or (2) by twisting or tugging the conduit to thereby reposition the cleaner body. As will be described hereinafter, repositioning subsystems for generating these mechanical forces can be located on the cleaner body and/or on the conduit. As will also be described hereinafter, a repositioning force can be generated by discharging a fluid flow from a location on the cleaner body and/or on the conduit.
It is preferable to introduce a short time delay between the motion sensor recognizing diminished velocity and the repositioning subsystem actually producing the repositioning force. This time delay, which can be introduced by component reaction time, enables the system to tolerate short term aberrations without initiating excessive repositioning.
In preferred embodiments of the invention, a device is incorporated to periodically, e.g., every 10-60 seconds, define a conditional repositioning state, which is ignored if the body""s velocity exceeds the threshold. However, if the motion sensor indicates that the body""s velocity is less than the threshold, concurrently with the conditional repositioning state being defined, then repositioning is initiated for a limited duration, e.g., 1 to 60 seconds, after which forward motion is resumed. An unconditional repositioning state is also preferably defined at a lower rate, e.g., every one to five minutes, for the purpose of repositioning the body regardless of the body""s velocity to enhance the randomness of traverse.
In a first preferred embodiment described hereinafter, the motion sensor and repositioning subsystem are mounted on the cleaner body. The motion sensor comprises a paddle mounted to close a bleed port when body velocity exceeds a certain threshold rate. With the bleed port closed, supplied positive pressure holds a repositioning actuator in a forward state. If body velocity diminishes below the threshold rate, the paddle will open the bleed port, allowing supplied positive pressure to switch the actuator to a reposition state. The actuator is configured to rotate the cleaner body with respect to a distal supply hose section. The actuator includes a linear drive member, e.g., a rack, mounted for movement between a first position when in the forward state and a second position when in the reposition state. The rack is engaged with a gear fixed relative to the distal hose section so that movement of the rack from the first position to the second position rotates the cleaner body around the distal section. Inasmuch as this rotation redirects the cleaner body propulsion subsystem, resumed forward motion will generally allow the body to avoid the obstruction which caused its velocity to diminish below threshold.
In a second preferred embodiment described hereinafter, the motion sensor and repositioning subsystem are mounted in a housing carried by the supply hose. Although the motion sensor so mounted responds to the hose velocity, since the hose is being dragged by the powered cleaner body, the hose velocity indirectly indicates cleaner body velocity and so can be used to initiate repositioning. The housing includes elements which functionally correspond to the elements described with respect to the first embodiment. However, instead of the aforementioned actuator to drive a rack, the second embodiment employs a small turbine to drive a gear which twists or rotates a portion of the supply hose distal section connected to the cleaner body. This action transfers a limited duration rotational force to the cleaner body to modify its position. Thereafter, resumed forward propulsion will generally free the body from the obstruction which caused its velocity to diminish below threshold.
In a third preferred embodiment described hereinafter, the motion sensor and repositioning subsystem are also mounted in a housing carried by the supply hose. The housing defines a nozzle for selectively discharging a water flow to produce a reaction force on the supply hose which is physically transferred by the hose to the connected cleaner body. The water flow discharge through the nozzle is controlled by a valve whose position is determined by a periodic controller and the position of a paddle mounted to sense cleaner body velocity. If body velocity diminishes below a certain threshold, the nozzle is caused to discharge a water flow for a limited duration to reposition the body. Thereafter, forward motion is resumed which will generally allow the body to resume its random traverse of the pool.
A fourth preferred embodiment described hereinafter is also configured for mounting on a housing carried by the supply hose. Similarly to the third embodiment, the fourth embodiment housing defines a nozzle for selectively discharging a water flow to produce a reaction force on the supply hose. This reaction force is physically transferred by the supply hose to the cleaner body to reposition it. The valving to control the discharge in the fourth embodiment is implemented differently from the third embodiment, as well as the controller mechanism for responding to the motion sensor.